By the numbers: According to preliminary August survey results, the University of Michigan’s consumer sentiment index plunged to 70.2 from 81.2 in July.

This was the lowest reading since December 2011 and was much worse than the 81.0 level expected by economists.

The current economic conditions subindex declined by 6.6 points to 77.9, while the consumer expectations subindex dropped 13.8 points to 65.2.

What they’re saying: “It’s just one data point, but sobering,” CIBC Private Wealth CIO David Donabedian says. “It reinforces our expectations of higher market volatility over the course of the year.”